It's a great elbow pad; it is comfortable, does not get hot and you really do forget that you're wearing it (assuming it is sized correctly).
The reason it is only 3 instead of 5 stars is simply that it will not stay put. I'd seen this mentioned in other reviews, but I was hoping they had the wrong size. I got the smallest size that would fit on my arm, and I've already had a crash where my entire elbow was scraped up (and bleeding) right where the elbow pad is normally. It moved as soon as it made contact.
I'm not sure what could be done to fix it, but as it is I don't trust them completely. Perhaps the upper end needs to be longer to provide more hold, or it needs some form of grippy material on the inside. That would definitely affect comfort, but I'd rather have slightly uncomfortable elbow pads versus bloody elbows.
I did contact their customer service to see if perhaps I did something wrong, but they quickly tried to sell my their latest version of this product (which I already). When I pointed that out, I stopped getting responses.